A geothermal heat pump system is a heating and cooling system that uses the Earth’s ability to store heat in the ground. A geothermal heat pump uses the Earth as either a heat source, when operating in heating mode, or a heat sink, when operating in cooling mode.

The ground a few feet below the surface has a very stable temperature throughout the year. Geothermal heat pumps draw that available heat in the winter and sink heat into the ground in the summer. A conventional furnace or boiler burns a fossil fuel to produce heat. In contrast, geothermal systems simply transfer heat from one place to another.

Geothermal heat pumps are also known as “ground-source heat pumps.” They are different from typical heat pumps in homes where the heat source is the air. Both types work on the same thermodynamic principle: heat can be pumped from a lower temperature source to a higher temperature source.

The switch to geothermal heat is not detectable. Faculty, staff, and students do not notice a difference in temperature in offices and classrooms.

The system is composed of four key components: boreholes, energy stations, hot and cold district loops of water-filled pipes, and building interfaces.

Borehole Fields

Borehole fields are spaced around campus. The fields contain a series of closed pipes that are installed vertically in the ground. Ball State’s loop consists of approximately 3,600 boreholes, 400 to 500 feet deep. The boreholes are 4 to 5 inches in diameter. During Phase 1, 1,800 boreholes were drilled. Phase 2 will include the drilling of 1,800 additional boreholes, ending with more than 1,000 miles of geothermal piping installed. Pipe inserted into a borehole is joined with a U-shaped cross connector at the bottom of the hole, allowing water to circulate through the closed piping system. The borehole is commonly filled with a grout surrounding the pipe to provide a good thermal conductor to the surrounding soil or rock to maximize the transfer of heat.

Ball State’s closed loop system circulates water. In colder climates, similar systems require the use of an antifreeze such as food quality propylene glycol. Ball State’s system does not require antifreeze and uses only fresh water. There is no direct interaction between the water in the system and the Earth, only heat transfer across the pipe.

Energy Stations

Energy stations house the equipment that are the workhorse of the system. A North District Energy Station was built in 2011, and a south station will be built in 2012–13. Each energy station will contain heat pump chillers that use an environmentally friendly refrigerant, R134A. The heat pump chillers through a compression cycle moves energy much the same way as a common household refrigerator. Energy or heat can be either pulled from or sank into the ground. The heat exchange will allow for the simultaneous production of cold water, 42 degree Fahrenheit, and hot water, 150 degrees Fahrenheit.

District Loops

Hot and cold water is routed throughout the campus via two separate district loops, one for heating purposes and one for cooling purposes. The campus had an existing district cold water distribution system. The geothermal conversion project includes the installation of a new district hot water distribution system throughout campus.

Building Interface

The district loops supply buildings’ demand for heating or cooling. The hot and cold water passes through heat exchangers (similar to a radiator in a car) and fans blow air across the heat exchangers to maintain the correct temperature in buildings as called for by the occupants.

The system uses American-made products and is being built by U.S. contractors, many of them from Indiana.

The impact of the project is immediate creating an opportunity for an estimated 2,300 direct and indirect jobs through Phase 1 and 2. Manufacturers supplying the project increase production and keep more workers on the job.

We find history repeating itself. The Ball brothers came to Muncie to reduce costs for their glass business by using “free” energy in the form of natural gas pulled from the ground. Now, the university they founded will save $2 million annually in operating costs by using a different form of “free” energy pulled from the same ground in thermal energy.

Environmental

By taking the current, aging boilers offline, the university will be able to reduce the amount of carbon dioxide it adds to the atmosphere by a substantial amount—about 85,000 tons annually. The net result of switching to the geothermal system will allow Ball State to cut its carbon footprint roughly in half.

This project is debunking the erroneous assumption that alternative energy projects are always too expensive or impractical to be adopted by cost-conscious businesses and consumers. The best ones, like Ball State’s geothermal energy system, are a boon to the economy as well as the environment.

By taking the current, aging boilers offline, the university will be able to reduce the amount of carbon dioxide it adds to the atmosphere by a substantial amount—about 85,000 tons annually. The net result of switching to the geothermal system will allow Ball State to cut its carbon footprint by nearly half.

There is no direct interaction between the water in the system and the earth, only heat transfer through the pipes. Ball State’s closed loop system circulates water. In colder climates, similar systems require the use of an antifreeze such as food quality propylene glycol. Ball State’s system does not require antifreeze and uses only water.

Geothermal technology has been used for decades in residential and commercial applications. For example, One American Square—approximately 1 million square feet—in Indianapolis has been heated and cooled since 1982 with four wells supporting its open loop system. The Galt House in Louisville, Kentucky, also uses open loop geothermal heating and cooling technology.

It’s the scope of the system—including 47 buildings, 5.5 million square feet, and more than 731 acres—that makes the new Ball State system unique.

The availability of very large capacity heat pump chillers that have come to market in only recent years makes the project possible today. The university has consulted the U.S. Department of Energy’s National Renewable Energy Laboratory, Oak Ridge National Laboratory, and the country’s leading firms in this area. Ball State has also received a ringing endorsement from a past president of the American Society of Heating, Refrigeration, and Air-Conditioning Engineers (ASHRAE). ASHRAE sets the national standards for heating and cooling equipment.

The boreholes are being installed at two locations on campus. All areas of campus where boreholes are installed will be restored to their original use and beauty. People using the parking lots and recreational fields do not notice they are atop a borehole field. See a map of the locations.

Two energy stations will house large-capacity heat pump chillers and pumps that will pump water through the system. The North District Energy Station was built in 2011. The south station will be housed within the current Central Chilling Plant.

Modest changes will be made inside campus buildings, involving mostly temperature control upgrades to current systems and a piping connection to the new district hot water loop. The switch to geothermal heat is not detectable. Faculty, staff, and students do not notice any difference in temperature in offices and classrooms.